Light emitting device and method of manufacturing the same

ABSTRACT

A light emitting device having a structure in which oxygen and moisture are prevented from reaching light emitting elements, and a method of manufacturing the same, are provided. Further, the light emitting elements are sealed by using a small number of process steps, without enclosing a drying agent. The present invention has a top surface emission structure. A substrate on which the light emitting elements are formed is bonded to a transparent sealing substrate. The structure is one in which a transparent second sealing material covers the entire surface of a pixel region when bonding the two substrates, and a first sealing material (having a higher viscosity than the second sealing material), which contains a gap material (filler, fine particles, or the like) for protecting a gap between the two substrates, surrounds the pixel region. The two substrates are sealed by the first sealing material and the second sealing material. Further, reaction between electrodes of the light emitting elements (cathodes or anodes) and the sealing materials can be prevented by covering the electrodes with a transparent protective layer, for example, CaF 2 , MgF 2 , or BaF 2 .

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/906,577, filed May 31, 2013, now allowed, which is a divisional ofU.S. application Ser. No. 13/188,513, filed Jul. 22, 2011, now U.S. Pat.No. 8,455,916, which is a continuation of U.S. application Ser. No.12/726,429, filed Mar. 18, 2010, now U.S. Pat. No. 7,985,606, which is adivisional of U.S. application Ser. No. 10/465,877, filed Jun. 20, 2003,now U.S. Pat. No. 7,700,958, which claims the benefit of a foreignpriority application filed in Japan as Serial No. 2002-197424 on Jul. 5,2002, all of which are incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having a circuitcomposed of a thin film transistor (hereinafter, TFT) and a method formanufacturing the semiconductor device. In particular, the presentinvention relates to an electronic device onboard an electric opticaldevice typified by a liquid crystal display panel and a light emittingdisplay device having an organic compound light emitting layer ascomponents.

A semiconductor device in this specification means comprehensivesemiconductor devices such as an electric optical device, asemiconductor circuit, and an electronic device.

2. Description of the Related Art

In recent years, study of a light emitting device having an EL elementas a self-luminous element has become vigorous. In particular, a lightemitting device using an organic material as an EL material hasattracted an attention. The light emitting device is also referred to asan EL display.

Note that an EL element includes a layer containing an organic compoundthat emits light by applying an electric field (hereinafter, an ELlayer), an anode, and a cathode. Luminescence generated by an organiccompound is fluorescence that generates upon returning of electrons fromthe singlet excited state to the ground state and phosphorescence thatgenerates upon returning of electrons from the triplet excited state tothe ground state. A light emitting device fabricated by a depositiondevice and a deposition method is applicable to both kinds ofluminescence.

A light emitting device has no viewing angle difficulties for itsself-luminous property differently from a liquid display device. Thusthe light emitting device is more suitable for using at outside than theliquid crystal display device. Various types of usage have been proposedfor the light emitting device.

An EL element has a structure in which a pair of electrodes sandwich anEL layer between each other, generally, a laminated structure.Typically, a laminated structure, “a hole transporting layer, a lightemitting layer, an electron transporting layer” proposed by Tang et al.of Kodak Eastman Company is generally known. The structure has greatlyhigh luminous efficiency and employed by almost all light emittingdevices that are under development now.

Another structure such as “an anode, a hole transporting layer, a lightemitting layer, and an electron transporting layer” or “an anode, a holeinjecting layer, a hole transporting layer, a light emitting layer, anelectron transporting layer, and an electron injecting layer” can bealso applicable. Fluorescent pigments can be doped to the light emittinglayer. For forming these layers, either a low molecular material or ahigh molecular material can be used.

In this specification, an EL layer is a generic term used to refer toall layers formed between a cathode and an anode. Therefore all of eachthe above-mentioned hole injecting layer, hole transporting layer, lightemitting layer, electron transporting layer, electron injecting layer isan EL layer.

In this specification, a light emitting element that is formed by acathode, an EL layer, and an anode is referred to as an EL element.There are two kinds for forming the EL element; a simple matrix that anEL layer is sandwiched between two kinds of striped electrodes that runat right angles to one another, or an active matrix that an EL layer issandwiched between a pixel electrode and a counter electrode arranged inmatrix that are connected to a TFT. When the pixel density is becomehigh, it is considered that an active matrix has an advantage over asimple matrix because the active matrix can drive at low voltage forhaving switches in each pixel (or each dot).

Since an EL material is deterioratable resulted from being oxidized orabsorbed due to oxygen or moisture, there has been a problem that theluminous efficiency of a light emitting element is decreased or thelifetime thereof is shorted.

Conventionally, oxygen or moisture is prevented from penetrating into alight emitting element by encapsulating the light emitting element usingan encapsulating can, enclosing a dry air thereinto, and pasting dryingagent to the encapsulating can.

The conventional light emitting has the structure that has a lightemitting element in which an electrode on a substrate is formed as ananode, an organic compound layer is formed on the anode, and a cathodeis formed on the organic compound layer, and light generated in theorganic compound layer is emitted through the anode formed as atransparent electrode to a TFT (hereafter, the structure is referred toas a bottom emission).

Although an encapsulating can is possible to cover a light emittingelement in above bottom emission structure, the structure that anelectrode on a substrate is formed as an anode, an organic compoundlayer is formed on the anode, and a cathode is formed as a transparentelectrode (hereinafter, the structure is referred to as a top emission)cannot use the encapsulating can that is made from a light shieldingmaterial. A drying agent on the pixel portion disturbs the display inthe top emission structure. Further in order not to absorb, the dryingagent requires careful handling and quick enclosing.

Compared to a bottom emission structure, a top emission structurerequires few material layers through which light is emitted generated inan organic compound layer, and thereby can suppress stray light betweenmaterial layers having different reflective index.

An object of the present invention is to provide a light emitting deviceand a method for forming the light emitting device through which oxygenor moisture is prevented from penetrating into a light emitting element.Another object of the present invention is to encapsulate the lightemitting element with a few steps without enclosing drying agent.

The present invention has a top surface emission structure in which asubstrate, with light emitting elements formed thereupon, is bonded to atransparent sealing substrate. A pixel region is covered over its entiresurface by a transparent second sealing material when bonding the twosubstrates, and is surrounded by a first sealing material (having ahigher viscosity than the second sealing material) that contains a gapmaterial (filler, fine particles, or the like) for maintaining a gapbetween the two substrates. The first sealing material and the secondsealing material thus seal the light emitting element.

There is a fear in that air bubbles will remain in corners if a sealpattern shape for the first sealing material is formed into a squareshape, an inverted “c” shape, or a “U” shape, and the two substrates arebonded by dripping the low viscosity second sealing material thereon.

Therefore, in the present invention, a pattern shape of the firstsealing material is formed into a pattern having no bent portion (lineshape) without making the pattern shape into the square shape, theinverted “c” shape or the “U” shape. Opening portions (four locations)are formed in the corners, which allow air bubbles to escapetherethrough. By forming the opening portions, the low viscosity secondsealing material is pushed out in the direction of the opening portionof the corners when bonding the two substrates using the low viscositysecond sealing material. The two substrates can thus be sealed withoutair bubbles mixing in on the pixel region. In addition, a pattern forthe high viscosity first sealing material may be slightly curved so thatair bubbles do not form. Further, it is preferable that the substratesurfaces on the sealing side be smooth and have superior levelness sothat bubbles do not mix in.

Further, there are cases in which a circumferential portion of thesecond sealing material will spread out from the opening portions (fourlocations), forming a bulging out shape (protruding shape), dependingupon the viscosity of the second sealing material and the manner inwhich it is pushed out. There are also cases in which thecircumferential portion of the second sealing material will form a shapethat enters into the inside of the opening portions. Note that theadhesive strength between the two substrates can be increased in orderto increase the contact adhesive surface area if there is provided abulging out shape.

In either case, the high viscosity first sealing material functions tomaintain the substrate gap through the gap material, and to adjust theplanar shape of the low viscosity second sealing material. Further, thefirst sealing material can also serve as a mark when sectioning thesubstrate. For example, the substrate may be sectioned along the firstsealing material when manufacturing a plurality of panels on onesubstrate, that is, in the case of so-called multiple patterns.

Further, a location of maximum load applied when a shock is receivedfrom the outside can be set to the location of the first sealingmaterial (only the first sealing material has the gap material) disposedoutside of the pixel region, and the load can be prevented from beingapplied to the pixel region. Further, this is a structure in which thefirst sealing materials are symmetrically disposed, and loads areapplied uniformly and with a good balance. Shocks from the outside cantherefore be uniformly diffused. Further, the first sealing materialshave a symmetrical shape, and are disposed symmetrically, and thereforea very constant substrate gap can be maintained. That is, a lightemitting device having an even more robust mechanical strength can bemade by using the structure of the present invention.

Further, it is desirable that the substrate, through which light emittedfrom the light emitting elements passes, be thin for the top surfaceemission structure. Thin substrates have a disadvantage, however, inthat they are weak with respect to shocks. Nonetheless, a light emittingdevice capable of withstanding shocks form the outside can be made inaccordance with the present invention, even if a glass substrate or thelike, which tends to break relatively easily, is used as the substratethrough which light emitted from the light emitting elements passes.Further, there are no particular limitations placed on the transparentsubstrate used, and plastic substrates and the like can be used, forexample. It is preferable that a pair of substrates use substrateshaving the same thermal expansion coefficient in order to maintain theadhesive strength.

Further, by making the seal pattern of the first sealing material into asimple shape, other seal pattern forming methods can also be used, suchas a printing method, for example, in addition to a dispenser apparatus.

Further, the light emitting elements are sealed by the first sealingmaterial, the second sealing material, and the substrates, and thereforemoisture and oxygen can be effectively blocked. Note that it isdesirable to perform bonding of the pair of substrates under a reducedpressure or in a nitrogen atmosphere.

According to an aspect of the invention disclosed in this specification,there is provided a light emitting device including a pixel portionhaving a plurality of light emitting elements between a pair ofsubstrates, at least one of which has transmittivity, the light emittingelements each having:

-   -   a first electrode;    -   an organic compound layer on and in contact with the first        electrode; and    -   a second electrode on and in contact with the organic compound        layer; characterized in that:    -   the pair of substrates are fixed by a first sealing material        disposed surrounding the pixel portion, and a second sealing        material in contact with the first sealing material and covering        the pixel portion; and    -   the first sealing material has openings in four corners.

In the structure described above, it is characterized in that the firstsealing material has a linear shape and is disposed in the plane of thesubstrate, in parallel with an x-direction or a y-direction.

Further, in the structure described above, it is characterized in thatthe second sealing material is exposed by the openings, and thecircumference of the exposed second sealing material is curved, as shownby FIGS. 1A to 1C. A structure may also be adopted in which the secondsealing material is exposed at the openings, and the circumference ofthe exposed second sealing material protrudes from the openings as shownin FIG. 1A. Alternatively, a structure may also be adopted in which thesecond sealing material is exposed at the openings, and thecircumference of the exposed second sealing material is depressedinwardly from the opening portions, as shown in FIG. 1C.

Further, according to another aspect of the present invention, there isprovided a light emitting device including a pixel portion having aplurality of light emitting elements between a pair of substrates, atleast one of which has transmittivity, the light emitting elements eachhaving:

-   -   a first electrode;    -   an organic compound layer on and in contact with the first        electrode; and    -   a second electrode on and in contact with the organic compound        layer;

characterized in that:

-   -   a pair of first sealing materials sandwiching the pixel portion        are disposed in an x-direction, and another pair of the first        sealing materials are disposed in a y-direction;    -   a second sealing material fills a space between at least one        pair of the first sealing materials; and    -   the shape of the second sealing material has bilateral symmetry,        and is not limited to a linear shape provided that the second        sealing material is disposed symmetrically sandwiching the pixel        portion.

Further, in each of the structures described above, the first sealingmaterial contains a gap material that maintains a gap between the pairof substrates.

Further, in each of the structures described above, it is characterizedin that the second sealing material has higher transparency than thefirst sealing material.

Further, in each of the structures described above, it is characterizedin that the film thickness of the second electrode is from 1 nm to 10nm.

Further, in each of the structures described above, it is characterizedin that there is provided a protective layer having transparency andmade from CaF₂, MgF₂, or BaF₂, between the second electrode and thesecond sealing material.

Further, each of the structures described above is a light emittingdevice characterized in that light emitted from the light emittingelements is discharged through the second sealing material and one ofthe substrates.

Furthermore, the present invention can also be applied to double sidedlight emitting elements. In this case, each of the structures describedabove becomes a light emitting device characterized in that lightemitted from the light emitting elements includes: emitted light that isdischarged through the second sealing material and one of thesubstrates; and emitted light that is discharged through the othersubstrate.

Further, according to another aspect of the present invention in orderto realize each of the structures described above, there is provided amethod of manufacturing a light emitting device characterized byincluding the steps of:

-   -   forming one pair of first sealing materials on a first substrate        in an x-direction, and one pair of the first sealing materials        in a y-direction, opening a gap between each pair of the first        sealing materials, for a total of four of the first sealing        materials;    -   dripping a second sealing material having transparency onto a        region surrounded by the first sealing materials;    -   spreading out the second sealing material so that it fills at        least a space between mutually opposing first sealing materials        when bonding the first substrate and a second substrate, upon        which a pixel portion provided with light emitting elements is        formed, so that the pixel portion is disposed in a region        surrounded by the first sealing materials; and    -   curing the first sealing materials and the second sealing        material.

Further, according to another aspect of the present invention in orderto realize the top surface structure of FIG. 1A, there is provided amethod of manufacturing a light emitting device characterized byincluding the steps of:

-   -   forming one pair of first sealing materials on a first substrate        in an x-direction, and one pair of the first sealing materials        in a y-direction, opening a gap between each pair of the first        sealing materials, for a total of four of the first sealing        materials;    -   dripping a second sealing material having transparency onto a        region surrounded by the first sealing materials;    -   spreading out the second sealing material so that it protrudes        out from between adjacent first sealing materials when bonding        the first substrate and a second substrate, upon which a pixel        portion provided with light emitting elements is formed, so that        the pixel portion is disposed in a region surrounded by the        first sealing materials; and    -   curing the first sealing materials and the second sealing        material.

Further, a first sealing material and a second sealing material may alsobe formed on a second substrate, upon which a pixel portion is formed.According to another aspect of the present invention relating to amanufacturing method therefor, there is provided a method ofmanufacturing a semiconductor device characterized by including thesteps of:

-   -   forming one pair of first sealing materials on a first        substrate, upon which a pixel portion provided with light        emitting elements is formed, in an x-direction, and one pair of        the first sealing materials in a y-direction, opening a gap        between each pair of the first sealing materials, for a total of        four of the first sealing materials so as to surround the pixel        portion;    -   dripping a second sealing material having transparency onto the        pixel portion;    -   spreading out the second sealing material so that it fills at        least a space between mutually opposing first sealing materials        when bonding the first substrate and the second substrate; and    -   curing the first sealing materials and the second sealing        material.

In the structures relating to each of the manufacturing methodsdescribed above, the step of curing the first sealing materials and thesecond sealing material is a step of irradiating ultraviolet light or astep of heat treatment.

Further, in the structures relating to each of the manufacturing methodsdescribed above, it is characterized in that the second sealing materialhave a low viscosity than the first sealing material.

Further, in the structures relating to each of the manufacturing methodsdescribed above, it is characterized in that there is a further step ofsectioning the first substrate and the second substrate along the firstsealing materials after curing the first sealing materials and thesecond sealing material.

Further, although a metallic film having a thin film thickness andthrough which light passes, typically a film having aluminum as its mainconstituent, is used as the second electrode (cathode or anode) in thepresent invention, metallic thin films tend to easily oxidize, resultingin increasing their electrical resistance value. Further, there is afear in that the second electrode will react with the constituentscontained in the sealing materials. It is therefore desirable to coverthe second electrode (cathode or anode), which is formed on a layer thatcontains organic compounds, by using a transparent protective film ofCaF₂, MgF₂, or BaF₂, for example, thus preventing reaction between thesecond electrode and the sealing materials, and also effectivelyblocking oxygen and moisture without using a drying agent. Further, itis possible to form CaF₂, MgF₂, and BaF₂ by evaporation. Impurities canbe prevented from mixing in, and the electrode surfaces can be preventedfrom being exposed to the ambient atmosphere, by forming the cathode andthe transparent protective layer in succession by evaporation. Further,CaF₂, MgF₂, and BaF₂ are stable materials as compared with LiF, do notdiffuse to TFTs to exert almost no adverse influence.

Further, a region between the first electrode and the second electrodecan maintain a non-oxygen state with a concentration as close to zero aspossible, by using a metal (high work function material) having nooxygen atoms in its molecular structure, a tantalum nitride film, forexample, as the first electrode, by using a metal (low work functionmaterial) having no oxygen atoms in its molecular structure, an aluminumthin film, for example, as the second electrode, and in addition, bycovering these with CaF₂, MgF₂, or BaF₂.

Further, although there are no particular limitations placed on thematerial used as the second sealing material, provided that it is ahighly transparent material, it is desirable to use a material thatblocks oxygen and moisture. Further, ultraviolet light is alsoirradiated to the pixel portion during curing if an ultraviolet curingresin is used as the second sealing material. It is therefore desirableto form a layer that absorbs or reflects only ultraviolet light, ZnO orthe like, for example, on the transparent protective film.

According to another aspect of the invention disclosed in thisspecification, there is provided a light emitting device including apixel portion having a plurality of light emitting elements between apair of substrates, at least one of which has transmittivity, the lightemitting elements each having:

-   -   a first electrode;    -   a layer containing an organic compound on and in contact with        the first electrode; and    -   a second electrode on and in contact with the layer containing        an organic compound;    -   a protective layer having transparency on the second electrode        and made from CaF₂, MgF₂, or BaF₂; and    -   a sealing material having transparency on the protective film;

characterized in that:

-   -   the first electrode is a laminate of metallic layers; and    -   the second electrode is made from a single layer of a metallic        thin film having a film thickness of 1 nm to 10 nm.

The metallic thin film uses aluminum as its main constituent in thestructure described above. In the laminate of metallic layers, the layerthat contacts the layer containing the organic compound is a layer madefrom titanium nitride. Further, the metallic layer may also be a singlelayer composed of titanium nitride, instead of a laminate.

Further, in the structure described above, it is characterized in thatthe first electrode contacts a source region or a drain region of a TFT,or the first electrode is electrically connected to the source region orthe drain region of the TFT.

Further, in the structure described above the metallic thin film is onand contacting a layer made from CaF₂, MgF₂, or BaF₂ that has a thinnerfilm thickness than the metallic layer. In addition, there is a layermade from CaF₂, MgF₂, or BaF₂ on and contacting the metallic thin film,and having a thicker film thickness than the metallic thin film. Thatis, the metallic thin film is sandwiched and protected by the layersmade from CaF₂, MgF₂, or BaF₂.

Further, in the structure described above, it is characterized in thatthe pair of substrates are fixed by a first sealing material disposedsurrounding the pixel portion, and a second sealing materials thatcontacts the first sealing material and covers the pixel portion and thefirst sealing material has openings in its four corners.

Note that the light emitting elements (EL elements) have a layer(hereinafter referred to as an EL layer) that contains an organiccompound, in which luminescence (electroluminescence) developing byadding an electric field is obtained, an anode, and a cathode. Lightemission when returning to a base state from a singlet excitation state(fluorescence) and light emission when returning to a base state from atriplet excitation state (phosphorescence) exist as types of organiccompound luminescence. Light emitting devices manufactured in accordancewith the present invention can be applied to the use of either type oflight emission.

The light emitting elements having the EL layer (EL elements) have astructure in which the EL layer is sandwiched between the pair ofelectrodes, and the EL layer normally has a laminate structure. Thelaminate structure of a hole transporting layer, a light emitting layer,and an electron transporting layer, that has been proposed by Tang etal. of Eastman Kodak Company can be given as a typical example. Thisstructure has extremely high light emission efficiency, and nearly alllight emitting devices undergoing research and development at presentemploy this structure.

Further, a structure in which a hole injecting layer, a holetransporting layer, a light emitting layer, and an electron transportinglayer are laminated in order on an anode may also be used. A structurein which a hole injecting layer, a hole transporting layer, a lightemitting layer, an electron transporting layer, and an electroninjecting layer are laminated in order on an anode may also be used. Afluorescent pigment or the like may also be doped into the lightemitting layer. Further, these layers may be formed by using all lowmolecular weight materials, and may also be formed by using allpolymeric materials. Further, layers that contain inorganic materialsmay also be used. Note that all of the layers formed between the cathodeand the anode are referred to generically as EL layers in thisspecification. Hole injecting layers, hole transporting layers, lightemitting layers, electron transporting layers, and electron injectinglayers are therefore all included in the category of EL layers.

Further, there are no particular limitations placed on a method ofdriving a screen display in the light emitting device of the presentinvention. For example, a dot sequential driving method, a linesequential driving method, a surface sequential driving method, or thelike may be used. A line sequential driving method is typically used,and a time divided gray scale driving method or a surface area grayscale driving method may also be appropriately employed. Further, imagesignals input to a source line of the light emitting device may beanalog signals and digital signals. Driving circuits and the like may beappropriately designed according to the image signals used.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1C are diagrams showing Embodiment Mode 1;

FIGS. 2A and 2B are diagrams showing Embodiment Mode 1;

FIGS. 3A and 3C are diagrams showing Embodiment Mode 2;

FIGS. 4A to 4E are diagrams showing Embodiment Mode 3;

FIGS. 5A and 5B are diagrams showing a structure of an active matrixlight emitting device (Embodiment 1);

FIG. 6 is a diagram showing Embodiment Mode 1;

FIGS. 7A and 7B are diagrams showing Embodiment 2;

FIG. 8 is a diagram showing transmittivity of sealing materials;

FIG. 9 is a diagram showing a relationship between filler diameter andadhesive strength;

FIGS. 10A to 10F are diagrams showing examples of electronic equipment(Embodiment 3); and

FIGS. 11A to 11C are diagrams showing examples of electronic equipment(Embodiment 3).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment modes of the present invention will be explained below.

Embodiment Mode 1

FIG. 1A is a top view of an active matrix light emitting device thatimplements the present invention.

In FIG. 1A, reference numeral 11 denotes a first substrate, referencenumeral 12 denotes a second substrate, reference numeral 13 denotes apixel portion, reference numeral 14 denotes a driver circuit portion,reference numeral 15 denotes a terminal portion, reference numeral 16denotes first sealing materials, and reference numeral 17 a denotes asecond sealing material.

There are no specific limitations placed on the material used for thefirst substrate 11. It is preferable, however, to use substrates havingidentical thermal expansion coefficients for the first substrate H andthe second substrate 12 because the two substrates are bonded together.A substrate having transparency, for example, a glass substrate, aquartz substrate, or a plastic substrate, is used for the firstsubstrate 11 material if a bottom surface emission light emitting deviceis manufactured. Further, a semiconductor substrate or a metallicsubstrate can also be used if a top surface emission light emittingdevice is manufactured. The pixel portion 13, which has a plurality oflight emitting elements, the driver circuit portion 14, and the terminalportion 15 are formed on the first substrate 11.

An example in which the first sealing materials 16 are disposedsurrounding the pixel portion 13 and the driver circuit portion 14 isshown here. Further, a portion of one of the first sealing materials 16overlaps with the terminal portion 15 (or a wiring that extends from aterminal electrode). Note that the first sealing materials 16 contain agap material in order to maintain a space between the pair ofsubstrates. The first sealing materials 16 contain the gap material, andtherefore it is preferable that the first sealing materials 16 do notoverlap with elements (such as TFTs), so that shorts and the like do notdevelop when a load of some type is imparted. Further, the shape of thetop surface of the first sealing materials is linear, and there areopenings in four corners. In other words, two of the first sealingmaterials 16 are disposed in parallel in an x-direction, sandwiching thepixel portion, and two of the first sealing materials 16 are disposed inparallel in a y-direction, sandwiching the pixel portion. The totalnumber of the first sealing materials disposed is four.

Further, the second sealing material 17 a, at minimum, fills a spacebetween a pair of the first sealing materials 16. The pair of substratesis fixed by the first sealing materials 16, which are disposedsurrounding the pixel portion, and by the second sealing material 17 a,which contacts the first sealing materials and covers the pixel portion.

Further, the second sealing material 17 a is a colorless, transparentmaterial and does not contain the gap material. It therefore has highertransmittivity of light than the first sealing materials 16. The secondsealing material 17 a is exposed in gaps, or openings, between the firstsealing materials, and has the top surface shape in which thecircumference of the exposed second sealing material 17 a has a curvedshape.

A mechanism for the second sealing material 17 a to take on the shapeshown in FIG. 1A will be explained below using FIGS. 2A and 2B. Anexample of a top view of a sealing substrate (a second substrate 22)before bonding is shown in FIG. 2A. An example of forming a lightemitting device having one pixel portion from a pair of substrates isshown in FIG. 2A.

Four first sealing materials 26 are formed first on the second substrate22 by using a dispenser, after which a second sealing material 27 ahaving a lower viscosity than that of the first sealing material isdripped thereon. Note that a top view of the second substrate with thesecond sealing material having dripped thereon corresponds to FIG. 2A.

A first substrate, on which a pixel portion 23 having light emittingelements, or a driver circuit portion 24, and a terminal portion 25 areformed, is then bonded to the second substrate. A top view immediatelyafter bonding the pair of substrates is shown in FIG. 2B. The viscosityof the first sealing material is high, and therefore it spreads out verylittle upon bonding. The viscosity of the second sealing material islow, however, and the second sealing material spreads out planarly uponbonding, as shown in FIG. 2B. The second sealing material is pushed outbetween the first sealing materials 26, that is, in the direction of anarrow in FIG. 2B, toward an opening portion. Air bubbles can thus bekept from existing in a region between the first sealing materials 26,which is filled by the second sealing material. The first sealingmaterial 26 does not mix with a second sealing material 27 b, even ifthere is contact, and the first sealing material 26 has a viscosity suchthat the position at which it is formed is not changed by the secondsealing material 27 b.

The second sealing material 27 b is exposed in the openings in FIG. 2B,and the circumference of the exposed second sealing material 27protrudes out from the openings. The distance between the ambientatmosphere and the pixel portion can be made larger by the secondsealing material 27 b protruding out from the openings, and in addition,oxygen and moisture can be blocked. Further, the total contact surfacearea is also increased, and therefore the bonding strength alsoincreases. Further, the circumference of the second sealing material 27b is curved in the openings.

Note that an example of bonding the substrates after forming the firstsealing materials or the second sealing material on the second substrate22 is shown here, but the present invention is not limited to thisstructure in particular. The first sealing materials or the secondsealing material may also be formed on the first substrate, on whichelements are formed.

The first sealing materials 26 and the second sealing material 27 b arethen cured by performing heat treatment or ultraviolet lightirradiation.

Portions of the second substrate 22 are sectioned next. Lines shown bydashed line segments in FIG. 2B become substrate cutting lines. Thecutting lines may be set parallelly along the first sealing materialsformed on the terminal portion 25 upon sectioning.

The shape of the second sealing material 17 a shown in FIG. 1A can thusbe obtained in accordance with the procedures shown above.

Further, although an example in which the second sealing material 17 aprotrudes out from the openings is shown in FIG. 1A, various othershapes can also be made by suitably changing the viscosity of, amountof, or material used in the second sealing material.

For example, a second sealing material 17 b may be exposed in theopenings, and the circumference of the exposed second sealing materialmay be curved as shown in FIG. 1B. The second sealing material does notprotrude out from the openings in FIG. 1B. The circumference of thesecond sealing material takes on a shape in which it fills the gaps ofthe first sealing materials, tracing an arc.

Further, a second sealing material 17 c may be exposed in the openings,and the circumference of the exposed second sealing material may becurved, depressed inwardly from the opening portions, as shown in FIG.1C.

Further, the first sealing materials are not limited to a linear shape,provided that they have bilateral symmetry and that they are disposedsymmetrically, sandwiching the pixel portion. For example, the shape ofthe first sealing materials may be curved slightly so that the lowviscosity second sealing material will spread out easily upon bonding,as shown in FIG. 6. In FIG. 6, reference numeral 16 d denotes firstsealing materials and reference numeral 17 d denotes a second sealingmaterial.

Embodiment Mode 2

A portion of a cross sectional structure of a pixel portion of thepresent invention is shown here in FIG. 3A.

In FIG. 3A, reference numeral 300 denotes a first substrate, referencenumerals 301 a and 301 b denote insulating layers, reference numeral 302denotes a TFT, reference numeral 308 denotes a first electrode, andreference numeral 309 denotes an insulator. Reference numeral 310denotes an EL layer, reference numeral 311 denotes a second electrode,reference numeral 312 denotes a transparent protective layer, referencenumeral 313 denotes a second sealing material, and reference numeral 314denotes a second substrate.

The TFT 302 (p-channel TFT) formed on the first substrate 300 is anelement for controlling current flowing in the light emitting EL layer310, and reference numeral 304 denotes a drain region (or a sourceregion) thereof. Further, reference numeral 306 denotes a drainelectrode (or a source electrode) that connects a first electrode andthe drain region (or the source region). Further a wiring 307, such asan electric power source line or a source wiring, is formed at the sametime as the drain electrode 306, using the same process. An example inwhich the first electrode and the drain electrode are formed separatelyis shown here, but they may also be formed at the same time. Aninsulating layer 301 a that becomes a base insulating film (a nitrideinsulating film as a lower layer, and an oxide insulting film as anupper layer here) is formed on the first substrate 300, and a gateinsulating film is formed between a gate electrode 305 and an activelayer. Further, reference numeral 301 b denotes an interlayer insulatingfilm made from an organic material or an inorganic material. Further,although not shown here, an additional TFT (n-channel TFT or p-channelTFT), or a plurality of TFTs, may also be formed in one pixel.Furthermore, although a TFT having one channel forming region 303 isshown here, the present invention is not limited in particular to this,and a TFT having a plurality of channels may also be used.

Further, the reference numeral 308 denotes the first electrode, that is,an anode (or a cathode) of an OLED. A film of an element selected fromthe group consisting of Ti, TiN, TiSi_(X)N_(Y), Ni, W, WSi_(X), WN_(X),WSi_(X)N_(Y), NbN, Mo, Cr, Pt, Zn, Sn, In, and Mo, or a film of an alloymaterial or a chemical compound material having one of these elements asits main constituent, or a laminate film of such films, may be used asthe first electrode 308 material at a total film thickness in a range of100 nm to 800 nm. A titanium nitride film is used as the first electrode308 here. It is preferable to increase the work function by irradiatingultraviolet light or performing plasma processing using chlorine gasover the surface, when using a titanium nitride film as the firstelectrode 308.

Further, the insulator 309 (also referred to as a bank, a sidewall, abarrier, an embankment, and the like) covers an edge portion of thefirst electrode 308 (and the wiring 307). Inorganic materials (such assilicon oxide, silicon nitride, and silicon oxynitride), photosensitiveorganic materials and non-photosensitive organic materials (such aspolyimide, acrylic, polyamide, polyimide amide, resist, andbenzocyclobutene), laminates of these materials, and the like can beused as the insulator 309. A photosensitive organic resin covered by asilicon nitride film is used here. It is preferable to provide a curvedsurface having a radius of curvature only in an upper edge portion ofthe insulator when using a positive type photosensitive acrylic as theorganic resin material, for example. Further, negative typephotosensitive organic materials, which become insoluble in etchants byexposure to light, and positive type photosensitive organic materials,which become soluble in etchants by exposure to light, can be used asthe insulator.

Furthermore, a layer 310 that contains an organic compound is formed byusing an evaporation method or an application method. Note that it ispreferable to perform vacuum heat treatment before forming the layer 310that contains the organic compound, thus performing degassing, in orderto improve reliability. For example, if an evaporation method is used,evaporation is performed in a film formation chamber that has beenvacuum evacuated to a pressure equal to or less than 5×10⁻³ Torr (0.665Pa), preferably between 10⁻⁶ and 10⁻⁴ Pa. The organic compound isgasified in advance by resistive heating when performing evaporation,and is dispersed toward the substrate by opening a shutter at the timeof evaporation. The gasified organic compound is dispersed upward, andis deposited on the substrate after passing through an opening portionformed in a metal mask.

For example, a white color can be achieved by laminating Alq₃, Alq₃ intowhich Nile red, which is a red color light emitting pigment, is partlydoped, Alg₃, p-EtTAZ, and TPD (aromatic diamine) in order using theevaporation method.

Further, if the layer containing the organic compound is formed by anapplication method that uses spin coating, it is preferable to fire thelayer by using vacuum heat treatment after its application. For example,an aqueous solution of poly-(ethylene dioxythiophene) and poly-(styrenesulfonic acid) (PEDOT/PSS), which acts as a hole injecting layer, may beapplied over the entire surface and fired. A solution of polyvinylenecarbazole (PVK) doped with a luminescence center pigment(1,1,4,4-tetraphenyl-1,3-butadiene (TPB),4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran (DCM1),Nile red, Coumarin 6, or the like), which acts as a light emittinglayer, may then be applied over the entire surface and fired. Note thatwater is used as a solvent for PEDOT/PSS, which does not dissolve inorganic solvents. Consequently, there is no danger of re-dissolution ifPVK is applied thereupon. Further, the solvents used for PEDOT/PSS andPVK are different, and therefore it is preferable that one filmformation chamber be not used for both. Furthermore, the layer 310containing an organic compound can be formed as a single layer, and1,3,4-oxadiazole derivative (PBD), which has electron transportingcharacteristics, may be dispersed in polyvinyl carbazole (PVK), whichhas hole transporting characteristics. In addition, white colorluminescence can be obtained by dispersing 30 wt % of PBD as an electrontransporting agent, and dispersing a suitable amount of four types ofpigments (TFB, Coumarin 6, DCM1, and Nile red).

Further, reference numeral 311 denotes the second electrode made from aconductive film, that is, an OLED cathode (or anode). A film of an alloysuch as MgAg, MgIn, AlLi, CaF₂, and CaN, or a film having transmittivityand formed by co-evaporation of aluminum with an element residing ingroup 1 or group 2 of the periodic table, may be used as the secondelectrode 311 material. A top emission type light emitting device thatemits light that passes through the second electrode is manufacturedhere, and therefore a 1 nm to 10 nm thick aluminum film, or an aluminumfilm that contains a minute amount of Li is used. It becomes possible toform the material contacting the layer 310, which contains an organiccompound, by using a material other than an oxide if a structure usingan Al film is employed as the second electrode 311, and the reliabilityof the light emitting device can be increased. Further, a layer (filmthickness 1 nm to 5 nm) having transmittivity and made from CaF₂, MgF₂,or BaF₂ may also be formed as a cathode buffer layer before forming the1 nm to 10 nm aluminum film.

Further, a supplemental electrode may also be formed on the secondelectrode 311, in a region that does not become a light emitting region,in order to make the cathode have lower resistance. Furthermore, thecathode may be formed selectively by using a resistive heating method inaccordance with evaporation, and using an evaporation mask, upon cathodeformation.

Further, reference numeral 312 denotes the transparent protective layerformed by evaporation, which protects the second electrode 311 that ismade from a metallic thin film. In addition, the transparent protectivelayer 312 is covered by a second sealing material 313. The secondelectrode 311 is an extremely thin metallic film, and thereforeoxidation and the like tend to develop easily with exposure to oxygen.There is a fear in that the second electrode 311 will react withsolvents contained in the sealing materials, changing its properties.Reaction of the second electrode 311 with solvents and the likecontained in the second sealing material 313 is prevented by coveringthe second electrode 311, which is made from this kind of metallic thinfilm, with the transparent protective layer 312, for example, CaF₂,MgF₂, or BaF₂. Oxygen and moisture can also be effectively blocked atthe same time, without using a drying agent. Further, it is possible toform CaF₂, MgF₂, and BaF₂ by evaporation. Impurity mix-in can beprevented, along with exposure of the electrode surface to the ambientatmosphere, by forming the cathode and the transparent protective layerin succession by using evaporation. In addition, the transparentprotective layer 312 can be formed while imparting almost no damage tothe layer containing the organic compound if evaporation is used. Thesecond electrode 311 may also be further protected by forming layershaving transmittivity, made from CaF₂, MgF₂, or BaF₂, on and under thesecond electrode 311, thus sandwiching it.

Further, a region between the first electrode and the second electrodecan maintain a non-oxygen state with a concentration as close to zero aspossible, by using a metal (high work function material) having nooxygen atoms in its molecular structure, a tantalum nitride film, forexample, as the first electrode, by using a metal (low work functionmaterial) having no oxygen atoms in its molecular structure, an aluminumthin film, for example, as the second electrode, and in addition, bycovering these with CaF₂, MgF₂, or BaF₂.

Further, the second sealing material 313 bonds the second substrate 314and the first substrate 300 by the method shown in Embodiment Mode 1.There are no particular limitations placed on the material for thesecond sealing material 313, provided that it is a material having lighttransmitting properties, and ultraviolet curing epoxy resins and thermalcuring epoxy resins are typically used. A highly heat resistant UV epoxyresin (product name 2500 Clear, manufactured by Electrolite Cooperation)having an index of refraction equal to 1.50, a viscosity equal to 500cps, a Shore D hardness equal to 90, a tensile strength equal to 3,000psi, a Tg point of 150° C., a volumetric resistivity equal to 1×10¹⁵Ω·cm, and a withstand voltage of 450 V/mil is used here. Further, theoverall transmittivity can be raised by filling the second sealingmaterial 313 between the pair of substrates. The transmittivity wasfound for the following cases: when the second sealing material fillsthe space between a pair of glass substrates; when the first sealingmaterial fills the space between a pair of glass substrates; and whennitrogen gas fills the space between a pair of substrates. As shown inFIG. 8, the transmittivity when the second sealing materials fills thespace between the pair of glass substrates shows a value equal to orgreater than 90% in a visible light region. Note that lighttransmittivity is shown in the vertical axis in FIG. 8, and wavelengthis shown on the horizontal axis.

Further, a simplified form of the laminate structure in the lightemitting region is shown in FIG. 3B. Emitted light is discharged in thedirection of the arrow shown in FIG. 3B.

Further, emitted light can be discharged from both the top surface andthe bottom surface if a first electrode 318 made from a transparentconductive film as shown in FIG. 3C is used as a substitute for thefirst electrode 308 made from a metallic layer. ITO (indium tin oxidealloy), an alloy of indium oxide and zinc oxide (In₂O₃, —ZnO) zinc oxide(ZnO), and the like may be used as the transparent conductive film.

Further, this embodiment mode can be freely combined with EmbodimentMode 1.

Embodiment Mode 3

A case of forming a plurality of pixel portions on one substrate, thatis, an example of multiple patterns, is shown in FIGS. 4A to 4E.

An example of forming four panels using one substrate is shown here.

First sealing materials 32 are formed first in a predetermined locationon a second substrate 31 by using a dispenser apparatus under an inertgas atmosphere. (See FIG. 4A.) A material that contains a filler(diameter 6 μm to 24 μm) and having a viscosity of 370 Pa·s is used as atranslucent sealing material for the first sealing materials 32.Further, data that shows the relationship between the size of the fillercontained in the sealing material and the adhesive strength is shown inFIG. 9. Furthermore, the first sealing material 32 can be formed byprint process because it has a simple sealing pattern. Next, atransparent second sealing material 33 is dripped on the regionsurrounded by the first sealing materials 32 (with openings in fourcorners) (see FIG. 4B).

Furthermore, a highly heat resistant UV epoxy resin (product name 2500Clear, manufactured by Electrolite Cooperation) having an index ofrefraction of 1.50 and a viscosity of 500 cps is used here.

The first substrate, on which pixel portions 34 are formed, and thesecond substrate, on which the sealing materials are formed, are thenbonded. (See FIG. 4C.) Note that it is preferable to perform annealingin a vacuum immediately before bonding the pair of substrates by usingthe sealing materials, thus performing degasification. The secondsealing material 33 spreads out so as to form a shape like that shown inFIG. 1B, and is made to fill a space between the first sealing materials32. Depending upon the shape and the arrangement of the first sealingmaterials 32, the second sealing material 33 can be made to fill thespace without the introduction of air bubbles. Ultraviolet lightirradiation is performed next, curing the first sealing materials 32 andthe second sealing material 33. Note that heat treatment may also beperformed in addition to ultraviolet light irradiation.

Scribe lines 35, shown by dashed lines, are formed next by using ascriber apparatus. (See FIG. 4D.) The scribe lines 35 may be formedalong the first sealing materials.

The substrate is sectioned next using a breaker apparatus. (See FIG.4E.) Four panels can thus be manufactured from one substrate.

Further, this embodiment mode can be freely combined with EmbodimentMode 1 or Embodiment Mode 2.

A further detailed explanation of the present invention, which has theabove structure, will be given by the embodiments shown below.

Embodiments Embodiment 1

One example of a light emitting device that has a light emitting elementincluding an organic compound layer as a fight emitting layer will bedescribed in this embodiment with reference to FIG. 5.

FIG. 5A is a top surface view of a light emitting device and FIG. 5B isa cross-sectional view of FIG. 5A taken along the line A-A′. A dottedline 1101 is a source signal line driving circuit, 1102 is a pixelportion, and 1103 is a gate signal line driving circuit. Referencenumeral 1104 is an enclosing substrate and 1105 is a sealing agent.Inside enclosed by the first sealing agent 1105 is filled with a secondtransparent sealant 1107. The second sealant 1107 is exposed at fourcorners.

Reference numeral 1108 is a source signal line driving circuit and awiring for transmitting signals inputted to the gate signal line drivingcircuit 1103, and receives a video signal and a clock signal from FPC1109 as an external input terminal. Though only FPC is shown here, aprint wiring board (PWB) may be attached to the FPC. A light emittingdevice in this specification includes not only a light emitting devicebody but also a light emitting device to which FPC or PWB are attached.

Next, the cross sectional structure will be explained with reference toFIG. 5B. A driving circuit and a pixel portion are formed on thesubstrate 1110. Here, the source signal line driving circuit 1101 as adriving circuit and the pixel portion 1102 are formed.

CMOS circuit is formed as a source signal line driver circuit 1101 bycombining an n-channel TFT 1123 and a p-channel TFT 1124. The TFTforming a driving circuit may be formed of known CMOS circuit, PMOScircuit, or NMOS circuit. This embodiment shows a built-in driver that adriving circuit is formed on a substrate, but not limited thereto. Thedriving circuit can be formed not on the substrate but at exteriorportion thereof.

The pixel portion 1102 is composed of a plurality of pixels including aswitching TFT 1111, a current control TFT 1112, and a first electrode(anode) 1113 connected electrically to a drain of the current controlTFT 1112.

Since a first electrode 1113 contacts directly to a drain of the TFT,the bottom layer of the first electrode 1113 is formed of a materialthat is made from silicon that can be an ohmic contact to the drain. Thesurface of the first electrode 1113 that contacts to an organic compoundlayer is preferable to be made from a material that has the large workfunction. When the first electrode is formed of three-laminatedstructure, for example, a titanium nitride film, an aluminum-based film,and a titanium nitride film, the first electrode can suppress resistanceas a wiring low, be a good ohmic contact to the drain, and function asan anode. In addition, the first electrode 1113 can be formed either ofa single layer of a titanium nitride film or a laminated structure ofthree or more layers.

Further, an insulator (referred to as a bank, a barrier, or the like)1114 is formed on both ends of the first electrode (anode) 1113. Theinsulator 1114 may be made from an organic resin film or an insulatingfilm containing silicon. Here, a positive photosensitive acrylic resinfilm is used for forming the insulator 1114 as shown in FIG. 5. Theinsulator 1114 may be covered with a protective film made from analuminum nitride film, an aluminum oxynitride film, or silicon nitridefilm. The protective film is an insulating film that is made fromsilicon nitride or silicon oxynitride as major components by DCsputtering or RF sputtering, or a thin film that is made from carbon asmajor components. When a silicon target is used for forming theprotective film in an atmosphere containing nitride and argon, a siliconnitride film can be formed. Or a silicon nitride target can also beused. The protective film can be formed by using a deposition deviceusing remote plasma. It is preferable that the thickness of theprotective film is formed to be thin as much as possible in order forlight to pass therethrough.

An organic compound layer 1115 is selectively formed by evaporationusing evaporation mask or ink-jet on the first electrode (anode) 1113. Asecond electrode (cathode) 1116 is formed on the organic compound layer1115. Consequently, the first electrode (anode) 1113, an organiccompound film 1115, and a light emitting element 1118 formed of thesecond electrode (cathode) 1116. Since an example that the lightemitting element emits white light is shown here, a color filter formedof a coloring layer 1131 and BM 1132 (for ease of illustration, an overcoat layer is not shown) is provided.

If organic compound layers that can achieve R, G, B luminescence areformed respectively, full color display can be realized without colorfilter.

In order for the light emitting element 1118 on the substrate 1110 to beencapsulated, an enclosing substrate 1104 is adhered using a firstsealant 1105 and a second sealant 1107. Preferred material for the firstsealant 1105 and the second sealant 1107 is epoxy resin. It ispreferable that the first sealant 1105 and the second sealant 1107 donot penetrate moisture or oxygen as much as possible.

In this embodiment, for the enclosing substrate 1104, a plasticsubstrate made from FRP (Fiberglass-Reinforced Plastics), PVF(polyvinylfluoride), Mylar, polyester, acrylic, or the like can be usedbesides a glass substrate or a quarts substrate. After the enclosingsubstrate is adhered using the first sealant 1105 and the second sealant1107, third sealant can be used for adhering the enclosing substrate1104 to cover the side faces (exposed faces).

Encapsulation of the light emitting element 1118 using the first sealant1105 and the second sealant 1107 can cut it off absolutely from theoutside and prevent moisture or oxygen that cause deterioration of anorganic compound layer from penetrating. Therefore the high reliablelight emitting device can be fabricated.

This embodiment can be freely combined with any of Embodiment Mode 1 to3.

Embodiment 2

In this embodiment, a different cross-sectional structure from that ofEmbodiment Mode 2 is shown in FIG. 7.

In FIG. 7A, reference numeral 700 is a first substrate, 701 a, 701 b areinsulating layers, 702 is a TFT, 710 is an EL layer, 711 is a secondelectrode, 712 is a transparent protective layer, 713 is a secondsealant, and 714 is a second substrate.

A TFT 702 (p-channel TFT) formed on a substrate 700 controls currentthat is flowing through EL layer 710 for emitting light. Referencenumeral 704 is a drain region (or a source region). Reference numeral705 is a gate electrode. Though not shown here, one or more TFT(n-channel TFT or p-channel TFT) or plural TFTs are provided to onepixel. Here, a TFT having one channel forming region 703 is illustrated,but not limited thereto, the TFT can have a plurality of channels.

FIG. 7A shows a structure in which a first electrodes 708 a to 708 cmade from laminate of metallic layers are formed, then, after aninsulator 709 (also referred to as a bank, barrier, or the like) forcovering both ends of the first electrode is formed, etching isconducted in a self-aligning manner using the insulator 709 as a mask,and then, a center portion of the first electrode is etched thinly toform steps at both ends thereof with etching a part of the insulator. Bythis etching, a center portion of the first electrode is made thin andflat, and both ends portion of the first electrode are made thick, thatis, a concave shape. Then, an organic compound layer 710 and a secondelectrode 711 are formed on the first electrode to complete the lightemitting element.

The structure shown in FIG. 7A is for increasing an amount of emissionthat is extracted a certain direction (in the direction through thesecond electrode) by reflecting or condensing the light in the lateraldirection by a slope formed in the step portions of the first electrode.

Thus, a slope portion 708 b is preferable to be made from metal thatreflects light, for example, materials made form aluminum or silver asmajor components. A center portion 708 a is preferable to be made froman anode material having large work function or a cathode materialhaving small work function. Since wiring 707 such as a power supplyinglight or a source wiring is formed simultaneously, low resistancematerial is preferable to be selected.

A preferable angle of gradient (also referred to as a taper angle) ismore than 50° and less than 60°, more preferably, 54.7°. In order forthe light reflected by a slope face of the first electrode not to bedispersed or strayed, an angle of gradient, a material and a thicknessof an organic compound layer, or a material and a thickness of thesecond electrode needs to be set appropriately.

In this embodiment, reference numeral 708 a is a lamination of titaniumfilm (60 nm in thick) and a titanium nitride film (100 nm in thick), 708b is an aluminum film containing Ti slightly (350 nm in thick), and 708c is a titanium film (100 nm in thick). 708 c protects 708 b to preventhillock or deterioration of the aluminum film. Or a titanium nitridefilm may be used as 708 c to give it light shielding property andprevent reflection of an aluminum film. In order for 708 a to be goodohmic contact to 704 made from silicon, a titanium film is used for thebottom layer of 708 a, however it is not limited thereto, anothermetallic films can be used. 708 a can be formed of a single layer of atitanium nitride film.

UV treatment or plasma treatment is needed because a titanium nitridefilm is used as an anode in this embodiment. However, plasma treatmentis conducted to a surface of the titanium nitride film simultaneouslywith conducting etching to 708 b, 708 c, thereby the titanium nitridefilm can be obtained large work function as an anode.

Anode materials that can be substitution of a titanium nitride film arean element selected from Ni, W, WSi_(x), WN_(x), WSi_(x)N_(y), NbN, Mo,Cr, Pt, Zn, Sn, In, or Mo, an alloy material, or compound material thatis composed of above elements as a major component. A film or alaminated film that is made from above elements or materials can be usedin the total thickness range of 100 nm to 800 nm.

In the structure shown in FIG. 7A, since etching is conducted in aself-aligning manner using the insulator 709 as a mask, there is no needto add more masks. Thus a top emitting structure light emitting devicecan be fabricated with a few masks and steps collectively.

FIG. 7B shows a different structure from that of FIG. 7A. An insulatinglayer 801 c is used as an interlayer insulating film, and the firstelectrode and a drain electrode (or a source electrode) are provided atdifferent layers. Consequently, the number of masks is increasing butthe luminous area can be enlarged.

In FIG. 7B, reference numeral 800 is a first electrode, 801 a, 801 b,and 801 c are insulating layers, 802 is a TFT (a p-channel TFT), 803 isa channel forming region, 804 is a drain region (or a source region),805 is a gate electrode, 806 is a drain electrode (or a sourceelectrode, 807 is a wiring, 808 is a first electrode, 809 is aninsulator, 810 is an EL layer, 811 is a second electrode, 812 is atransparent protective layer, 813 is a second sealant, and 814 is asecond substrate.

If a transparent conductive film is used as the first electrode 808,both top and bottom emitting structure light emitting device can befabricated.

This embodiment can be freely combined with any of Embodiment Mode 1 to3, and Embodiment 1.

Embodiment 3

By implementing the present invention, all of electronic apparatusintegrated with a module having an organic compound layer (active matrixtype EL module, passive matrix EL module) are completed.

As such electronic apparatus, a video camera, a digital camera, a headmount display (goggle type display), a car navigation apparatus, aprojector, a car stereo, a personal computer, a portable informationterminal (mobile computer, portable telephone or electronic book) andthe like are pointed out. FIGS. 10 and 11 show examples of these.

FIG. 10A is a personal computer which includes a main body 2001, animage input portion 2002, a display portion 2003 and a keyboard 2004.

FIG. 10B is a video camera which includes a main body 2101, a displayportion 2102, a voice input portion 2103, an operation switch 2104, abattery 2105, an image receiving portion 2106.

FIG. 10C is a mobile computer which includes a main body 2201, a cameraportion 2202, an image receiving portion 2203, an operation switch 2204and a display portion 2205.

FIG. 10D is a goggle type display which includes a main body 2301, adisplay portion 2302 and an arm portion 2303.

FIG. 10E is a player using a record medium recorded with programs(hereinafter, referred to as record medium) which includes a main body2401, a display portion 2402, a speaker portion 2403, a record medium2404 and an operation switch 2405. Further, the player uses DVD (DigitalVersatile Disc) or CD as a record medium and can enjoy music, enjoymovie and carry out the game or Internet.

FIG. 10F is a digital camera which includes a main body 2501, a displayportion 2502, an eye-piece portion 2503, an operation switch 2504 and animage receiving portion (not illustrated).

FIG. 11A is a portable telephone which includes a main body 2901, avoice output portion 2902, a voice input portion 2903, a display portion2904, an operation switch 2905, an antenna 2906 and an image inputportion (CCD, image sensor) 2907.

FIG. 11B is a portable book (electronic book) which includes a main body3001, display portions 3002, 3003, a record medium 3004, an operationswitch 3005, an antenna 3006.

FIG. 11C is the display which includes a main body 3101, a support base3102 and a display portion 3103.

Incidentally, the display shown in FIG. 11C is of a screen size ofmiddle or small type or large type, for example, a screen size of 5 to20 inches. Further, in order to form the display portion of this size,it is preferable to use a display portion having a side of a substrateof 1 m and carry out mass production by taking many faces. As describedabove, the range of applying the present invention is extremely wide andis applicable to a method of fabricating electronic apparatus of all thefields. Further, the electronic apparatus of the embodiment can berealized by using a constitution comprising any combination ofEmbodiment Modes 1 to 3 and Embodiments 1 and 2.

In accordance with the present invention, a transparent sealing materialcan be made to fill a space, without containing air bubbles, uponbonding of a pair of substrates. A light emitting device having highreliability can therefore be obtained.

Further, a region between a first electrode and a second electrode canmaintain a non-oxygen state with a concentration as close to zero aspossible by using a metal (high work function material) having no oxygenatoms in its molecular structure, a tantalum nitride film, for example,as the first electrode, by using a metal (low work function material)having no oxygen atoms in its molecular structure, an aluminum thinfilm, for example, as the second electrode, and in addition, by coveringthese with CaF₂, MgF₂, or BaF₂. A light emitting device with highreliability can therefore be obtained.

What is claimed is:
 1. A light emitting device comprising: a firstsubstrate; a plurality of light emitting elements over the firstsubstrate; a second substrate over the first substrate and the pluralityof light emitting elements, a first sealing material interposed betweenthe first and second substrates and surrounding the plurality of lightemitting elements, wherein the first sealing material has a first end, asecond end, and an opening between the first end and the second end; anda second sealing material interposed between the first and secondsubstrates and covering the plurality of light emitting elements,wherein the second sealing material is surrounded by the first sealingmaterial, wherein the first and second sealing materials are differentfrom each other.
 2. The light emitting device according to claim 1,wherein each of the plurality of light emitting elements comprises: afirst electrode over the first substrate; a layer comprising an organiccompound over the first electrode; and a second electrode over the layercomprising the organic compound.
 3. The light emitting device accordingto claim 1, wherein the second substrate has a plurality of colorfilters above the plurality of light emitting elements.
 4. The lightemitting device according to claim 1, wherein the first sealing materialcontains a gap material that maintains a gap between the first andsecond substrates.
 5. The light emitting device according to claim 1,wherein the second sealing material has higher transparency than thefirst sealing material.
 6. The light emitting device according to claim1, further comprising an insulating layer between the plurality of lightemitting elements and the second sealing material.
 7. The light emittingdevice according to claim 1, wherein light emitted from the plurality oflight emitting elements passes through the second sealing material andthe second substrate.
 8. The light emitting device according to claim 1,wherein light emitted from the plurality of light emitting elementspasses through the second sealing material and the second substrate, andthrough the first substrate.
 9. The light emitting device according toclaim 1, further comprising a driver circuit portion over the firstsubstrate, the driver circuit portion covered with the second sealingmaterial.
 10. The light emitting device according to claim 1, whereinthe light emitting device is incorporated in at least one selected fromthe group consisting of a video camera, a digital camera, a goggle-typedisplay, a navigation system, a personal computer, a DVD player, anelectronic play equipment, a portable information terminal, a portabletelephone, an electronic book, and a display.
 11. A light emittingdevice comprising: a first substrate; a plurality of light emittingelements over the first substrate; a second substrate over the firstsubstrate and the plurality of light emitting elements; a first sealingmaterial interposed between the first and second substrates and providedoutside the plurality of light emitting elements, wherein the firstsealing material has a first end, a second end, and an opening betweenthe first end and the second end; and a second sealing materialinterposed between the first and second substrates and covering theplurality of light emitting elements, wherein the second sealingmaterial is surrounded by the first sealing material, wherein the firstand second sealing materials are different from each other.
 12. Thelight emitting device according to claim 11, wherein, each of theplurality of light emitting elements comprises: a first electrode overthe first substrate; a layer comprising an organic compound over thefirst electrode; and a second electrode over the layer comprising theorganic compound.
 13. The light emitting device according to claim 11,wherein the second substrate has a plurality of color filters above theplurality of light emitting elements.
 14. The light emitting deviceaccording to claim 11, wherein the first sealing material contains a gapmaterial that maintains a gap between the first and second substrates.15. The light emitting device according to claim 11, wherein the secondsealing material has higher transparency than the first sealingmaterial.
 16. The light emitting device according to claim 11, furthercomprising an insulating layer between the plurality of light emittingelements and the second sealing material.
 17. The light emitting deviceaccording to claim 11, wherein light emitted from the plurality of lightemitting elements passes through the second sealing material and thesecond substrate.
 18. The light emitting device according to claim 11,wherein light emitted from the plurality of light emitting elementspasses through the second sealing material and the second substrate, andthrough the first substrate.
 19. The light emitting device according toclaim 11, further comprising a driver circuit portion over the firstsubstrate, the driver circuit portion covered with the second sealingmaterial.
 20. The light emitting device according to claim 11, whereinthe light emitting device is incorporated in at least one selected fromthe group consisting of a video camera, a digital camera, a goggle-typedisplay, a navigation system, a personal computer, a DVD player, anelectronic play equipment, a portable information terminal, a portabletelephone, an electronic book, and a display.
 21. A light emittingdevice comprising: a first substrate; a plurality of light emittingelements over the first substrate; a second substrate over the firstsubstrate and the plurality of light emitting elements, a first sealingmaterial interposed between the first and second substrates andsurrounding the plurality of light emitting elements, wherein the firstsealing material has a first end, a second end, and an opening betweenthe first end and the second end; a second sealing material interposedbetween the first and second substrates and covering the plurality oflight emitting elements, wherein the second sealing material issurrounded by the first sealing material; and a connecting terminalconfigured to connect to an FPC over the first substrate, the connectingterminal provided outside of the first sealing material and the secondsubstrate, wherein the first and second sealing materials are differentfrom each other.
 22. The light emitting device according to claim 21,wherein, each of the plurality of light emitting elements comprises: afirst electrode over the first substrate; a light emitting layer overthe first electrode; and a second electrode over the light emittinglayer.
 23. The light emitting device according to claim 21, wherein thesecond substrate has a plurality of color filters above the plurality oflight emitting elements.
 24. The light emitting device according toclaim 21, wherein the first sealing material contains a gap materialthat maintains a gap between the first and second substrates.
 25. Thelight emitting device according to claim 21, wherein the second sealingmaterial has higher transparency than the first sealing material. 26.The light emitting device according to claim 21, further comprising aninsulating layer between the plurality of light emitting elements andthe second sealing material.
 27. The light emitting device according toclaim 21, wherein light emitted from the plurality of light emittingelements passes through the second sealing material and the secondsubstrate.
 28. The light emitting device according to claim 21, whereinlight emitted from the plurality of light emitting elements passesthrough the second sealing material and the second substrate, andthrough the first substrate.
 29. The light emitting device according toclaim 21, further comprising a driver circuit portion over the firstsubstrate, the driver circuit portion covered with the second sealingmaterial.
 30. The light emitting device according to claim 21, whereinthe light emitting device is incorporated in at least one selected fromthe group consisting of a video camera, a digital camera, a goggle-typedisplay, a navigation system, a personal computer, a DVD player, anelectronic play equipment, a portable information terminal, a portabletelephone, an electronic book, and a display.
 31. The light emittingdevice according to claim 1, wherein a part of the second sealingmaterial spreads out of the opening.
 32. The light emitting deviceaccording to claim 1, wherein the opening is not overlapping with theplurality of light emitting elements.
 33. The light emitting deviceaccording to claim 3, wherein the second sealing material is in contactwith the plurality of color filters.
 34. The light emitting deviceaccording to claim 11, wherein a part of the second sealing materialspreads out of the opening.
 35. The light emitting device according toclaim 11, wherein the opening is not overlapping with the plurality oflight emitting elements.
 36. The light emitting device according toclaim 13, wherein the second sealing material is in contact with theplurality of color filters.
 37. The light emitting device according toclaim 21, wherein a part of the second sealing material spreads out ofthe opening.
 38. The light emitting device according to claim 21,wherein the opening is not overlapping with the plurality of lightemitting elements.
 39. The light emitting device according to claim 23,wherein the second sealing material is in contact with the plurality ofcolor filters.